8 day itinerary for Germany

Frankly, to travel that far south, you'll be spending a lot of your limited time on the train. I would concentrate on northern Germany with Berlin as the southern/eastermost end point. Google e.g. Lübeck, Hamburg, Bremen, Lüneburg, Celle, Göttingen, Hameln, Einbeck, Schwerin, Mageburg and for beautiful scenery Mecklenburg Lake District ("Mecklenburgische Seenplatte), or Darst/Zingst, Rügen, Usedom. You'll have more than enough to do there.

I appreciate your advice and suggestions. That is why I posted this question. Thanks so much.

One option might be to go the way from Kopenhagen via Flensburg and Schleswig to Lübeck by car and return to Copenhagen via Ferry from Travemünde to Trelleborg in Sweden 8hrs from where its only 45 min drive to Copenhagen

Just in case you want to return to Copenhagen

Lübeck
https://www.luebeck-tourismus.de/

Travemünde
https://www.travemuende-tourismus.de/

Ferry
https://www.ttline.com/en/sweden-ferries/travemuende-trelleborg/

Flensburg
https://www.flensburg.de/?La=2

Schleswig
https://www.ostseefjordschlei.de/english

Haitabu
https://haithabu.de/en/homepage

Having more time a trip to Schwerin 1hr east of Lübeck and Wismar 45min north of Schwerin is possible

Schwerin
https://www.schwerin.de/kultur-tourismus/

Wismar
https://www.wismar.de/Tourismus/

Otherwise
I would definetaly fly to places like Berlin or Munich and see the cities and souroundings.

I spent several days in Munich and the Chiemgau and Allgäu and can give tips when you plan to go there.

This is really helpful. Thanks so much.

8 days, I suggest that you pick either Berlin area or Bavaria, not try to do both.

Also, you would need more time in Berlin than three nights.

Good advice above. I have done Copenhagen to northern Germany twice in recent years. Once last summer 2023 and once just before Covid. I can’t add much to the great ideas in sla and uwe’s posts, but just wanted to agree that driving is easy in the area, as is flying or train. We used Hamburg as a base on both trips. Last summer’s trip we flew one way from Copenhagen and returned by train with a stop in Odense, Denmark which you might consider for a charming small town. Rick doesn’t mention anything north of Hamburg. There are several good guide books and many websites with great info and suggestions.

I visited Berlin on a separate trip. There is a lot to see there with day trips to Potsdam. If you wanted to include it and don’t mind city bases, you could probably fly or train between Berlin for 4 nights and Hamburg 3. Train from Hamburg to Bremen or Lubeck for the smaller town.

I'll cast my vote for Berlin and the emphasis of just staying north. I've been to quite a few of the smaller cities already mentioned and enjoyed them all.

Berlin can easily take up most of your allotted time on it's own ... throw in a day trip to Potsdam and Leipzig (you'll want to travel by DB ICE trains) and woosh, there goes 8 days of quality sightseeing time.

You all have been incredibly helpful. We will definitely stay north. I think making Hamburg and Berlin the bases makes a lot of sense.
Good to know that there are guide books and websites just on the north. We do like to mix smaller towns with cities.

We generally rent a car when we go to Europe, but it does seem that the train system is very good. Do you recommend driving, flying or train from Copenhagen and then from Hamburg to Berlin.
While we are on the subject, I have Rick’s book and Copenhagen, but would appreciate your thoughts on highlights.
You all have been so helpful. Thank you again.

Lovely villages? Try a place called Glückstadt near Hamburg. Also, check out my posts on Hamburg and environs.